Time-of-flight mass spectrometry (concepts, achievements, and prospects)

A brief account is given of the history of dynamic mass spectrometers from the time of their advent. The reasons fur their relatively slow development in the 1930s-1940s of the last century are discussed. The general principle underlying the operation of all dynamic mass spectrometers, the difference between the velocities of motion of ions differing in mass but having the same energy, is pointed out. In accordance with its title, the review considers in more detail the history of development of time-of-flight (TOF) mass spectrometers and stresses their two major advantages over the static (magnetic) instruments, namely, the unlimited mass range and the possibility of obtaining extremely rapidly mass spectra over a broad ion mass range. This accounts for the fast progress in their performance and broad application in the period of 1960s-1980s, when investigation of heavy, thermally unstable organic molecules was started and efficient methods of producing their ions were developed. A serious limitation on the resolution of TOF instruments was largely removed after the formulation of the reflectron principle of TOF mass-spectrometer design. The problem of a further increase of the resolution of TOF systems is discussed. The illustrations of TOF reflectron applications are presented, and a possibility of analyzing molecules and clusters with masses of up to millions of daltons is pointed out. These merits have resulted in a sharp increase of production and a broadening of application potential of TOF mass spectrometers compared to the magnetic setups, particularly in the field of biophysics, biochemistry, and organic chemistry. In conclusion the broad horizons opened by the TOF magnetic-resonance mass spectrometers (MRMS) in the area of high-precision mass spectrometric measurements are pointed out. (Int J Mass Spectrom 206 (1001) 251-266) (C) 2001 Elsevier Science B.V.